A Fresnel lens sheet for use in a light-transmission screen employed for a conventional projection image display apparatus, which includes a plurality of prismatic Fresnel lens elements each having a riser facet and a Fresnel facet on a first surface of the lens, is configured so that a light projected from an optical projection unit passes through the riser facet of each Fresnel lens element, and then totally internally reflects by the Fresnel facet, to exit from a second surface of the lens. In such a Fresnel lens sheet, in order to efficiently reflect by the Fresnel facet a light that has entered the riser facet, it is preferable that an angle formed by the riser facet and the Fresnel facet be set to an acute angle of 45 degrees or less. However, a problem has been that when the Fresnel lens element is formed by setting the angle to the acute angle, breakage of the elements is prone to occur when handling them during transport, assembly or the like, thus leading to reduction in yield of the lens.
For that reason, a Fresnel lens sheet has been proposed that includes a plurality of prismatic Fresnel lens elements each having a top facet crossing between a riser facet and a Fresnel facet (for instance, Japanese Unexamined Patent Publication 2002-221611 (refer to paragraph 0020; FIG. 6)).
However, another problem has been that in situations where a top facet is formed so as to cross between the riser facet and Fresnel facet of the Fresnel lens element, a light beam that has passed through the top facet becomes an unwanted light that exits in a direction differing from the original exit direction, which turns out to be a double image, thereby leading to reduction of the image quality.